The detection of icing or ice-forming conditions on a surface is desirable and of advantage in many applications. For example, detection of icing conditions on roadways would enable a driver to be informed that ice is present on the roadway so the driver could to adjust the style of driving accordingly or discontinue driving altogether before an accident occurs. In rail system applications, it is highly desirable to determine when icing occurs on the rails, so that the rail operator may take counteractive steps, for example at the beginning of a sanding operation wherein sand is drizzled onto the rails ahead of the locomotive (for example) to ensure that traction is maintained. Once traction is lost in a rail system as a result of icing, it is extremely difficult to regain traction.
Heretofore, various methods have been employed to attempt detection of icing. These methods have included placing temperature sensors near the road surface to provide ambient air temperature reading. Often such detectors were combined with moisture detectors and a decision was made as to icing based on the presence of moisture and the ambient air temperature. However, such methods are not always able to accurately predict icing since the ambient air temperature may be greatly different than the temperature of the road surface wherein the road surface may actually be in an iced state while the air temperature is somewhat above freezing. Inaccurate determinations can lead to an operator ignoring an icing detector's warning if the operator knows that the indicator does not provide an accurate warning at all times.
Other methods have employed a radiation source directed towards the roadway with a receiver in spaced relation to the transmitter so as to receive reflections from the road surface of the energy transmitted from the radiation source. Surface condition predictions were then made based on the absorption and reflection of the energy by the road surface. However, the use of a source and reflected energy reception complicates the installation of such a device and requires that both the source and the receiver be maintained in a clean state, free from dirt or other road debris which would obscure the emitter or receiver.
In aircraft applications, the ability to detect wing icing is of utmost importance, since ice formations on wings can degrade the aircraft's lift-to-drag ratio. Aircraft currently have a device to measure air temperature, called an OAT (outside air temperature) sensor. This instrument provides the pilot with temperature information all of the time, whether the aircraft is in the hanger, loading passengers, flying in clear air or penetrating an icing thunder head. Therefore, in cold weather, the OAT sensor could indicate freezing continuously whenever the temperature was below freezing. Such indications can be of limited usefulness since the OAT makes no environmental distinction and is therefore of limited assistance in detecting icing during night flights, for example, when pilots are unable to visually inspect wing surfaces for ice accumulation.
In applications where an optical/infrared type detector is employed in an external environment, the sensor elements are typically protected from the relatively harsh conditions. However, over time, dust, dirt, road spray, or the like result in the window, for example which protects the sensor from external elements, becoming contaminated or dirtied, and the dirt or other foreign material thereon will reduce the amount of infrared energy or the like transmitted through the window. Such contamination has required frequent cleaning of protective windows or the accuracy of the sensor would suffer.
The ability to detect icing conditions, particularly to detect imminent icing conditions, wherein an indication is provided that surface conditions of a roadway, for example, are close to the icing point is highly desirable and can greatly reduce the likelihood of accidents.
Use of cruise control devices in automobiles and trucks is becoming increasingly common. However, it can be dangerous to have a cruise control operating when driving on ice. Heretofore, it has been necessary that a vehicle operator recognize the icing condition and remember to manually disengage the cruise control to increase driving safety.
It is further desirable to be able to detect roadway or rail surface temperatures when such temperatures are exceedingly high, in order to allow an operator, of for example a truck, to adjust tire pressure or to cease operation altogether until the road surface temperature falls to a more desired level. In a rail application, the determination that the rails have become excessively hot can be a prime safety determination. In continuously welded rail systems, excessively hot weather can lead to warping of the rails due to thermal expansion, which increases the likelihood of derailment. If an operator is able to accurately determine the rail temperature, it would be possible to reduce the speed of the locomotive or to otherwise take precautions to avoid derailment.
In areas where roadway icing occurs, traction enhancing substances or agents are typically deployed, by a government agency or municipality, for example, in order to increase traction and/or remove ice from a roadway or prevent ice accumulations. Traction enhancing substances or agents include anti-icing agents, which prevent or retard the formation of ice, de-icing agents, which melt ice, and friction agents, such as sand and gravel, which provide additional traction and/or break up ice. Heretofore, deployment systems typically include a truck carrying a traction enhancing agent, which can comprise sand, salt, liquids or some other agent. The traction enhancing substance or agent can be in the form of a solid, such as pellets, in the form of a liquid, or a combination of solid and liquid.
In early systems, the traction enhancing agent was dispensed at a constant rate, and an operator had an on/off switch to start and stop the deployment. Such systems had the drawback of an inconsistent or uneven application rate, since when the deployment truck moved faster, less material per unit of road length would actually be applied. Conversely, when the deployment truck was temporarily slowed or stopped while the dispensing mechanism was still activated, an excessive amount of traction enhancing agent would be applied. Excessive application rates required more frequent re- filling of the deployment truck. Further, with traction enhancing agents that raise environmental pollution issues, the minimal amount necessary is desirably employed, in order to reduce the amount of or likelihood of pollution (as well as saving money).
To attempt to solve some of the application rate issues, sensors were added to factor in the relative speed of the deployment vehicle, and then control the application rate based thereon. Still further systems were developed that enabled a set rate of deployment, e.g. weight of material per distance traveled (typically pounds per lane mile in the United States of America). with such systems, an operator had only to set the deployment rate and control the on/off status of the deployment apparatus. Such systems were fine with simple single traction enhancing agent deployment systems. However, more advanced deployment strategies have been developed, including solid traction enhancing agent deployment systems that include pre-wetting of the traction enhancing agent (with a brine, for example) and dispensing of anti-icing chemicals. Such multi-mode systems require more complex control, as the dispensing of anti-icing agents is done prior to ice formation (e.g. when the road surface temperature is above freezing). In the case of dispensing salt as the traction enhancing agent, for example, a pre-wetting brine is desirably applied to the salt at certain road temperature ranges prior to dispensing or concurrently therewith, to increase the likelihood that the salt will immediately stick to the road surface and hasten the melting process. Such pre-wetting adds another factor that the operator of the dispensing truck must control, as road temperature is a critical factor in choosing pre-wetting.
Still further, for certain traction enhancing agents, salt, for example, as the road temperature becomes lower, a point is reached wherein the traction enhancing agent is no longer effective (e.g. the salt will not melt the ice once the temperature drops too low). At such temperatures, the operator must stop deployment of the traction enhancing agent, to avoid waste.
In the past, a second operator was added to a deployment truck, with the first operator's job being limited to driving the truck, and the second operator's job being to operate the dispensing controls, monitoring the outside air temperature, and stopping the deployment if the temperature got too low. However, multiple operators increase the cost, so the trend is to systems that can be operated by a single driver. Further, the air temperature can differ from the road temperature, and the most important factor is the actual road temperature. Still further, having the single driver control multiple aspects of traction enhancing agent deployment increases the chance of mis- deployment or an accident, since the operator can be kept busy just driving, even without having to control and monitor the various functions.